HYDROIDS OF THE” WOODS HOLE REGION. 
333 
Sertularella gayi (Lamx. ). Fig. 64. 
( Sertularia gayi. Lamx., Exposition Mctliodique, p. 12.) 
Trophosorne . — Like the last, but much more robust. Branches regularly pinnate and approximate. 
ILydrothecse much larger, often corrugated on the upper side. 
Gonosome . — Gonangia with a 2-toothed aperture. 
Distribution . — A specimen in the U. S. Fish Commission collection at Woods Hole bears the label 
“E. by S., Sankety Light, Nantucket, 25 fath.” This specimen lias much larger and coarser hydro- 
thecse than specimens from England, and may represent a distinct species. 
62. Sertularella rugosa (Linn.). 
THUIARIA. 
Tropliosomi '. — Colony branched; stem and branches divided into 
internodes each of which bears more than two opposite or subopposite 
hydrothecae which are usually deeply immersed in the stem. Hydro- 
thecae tubular, or flask-shaped, with bilabiate apertures. 
Gonosome . — Gonangia much like those of Sertularia. 
Key to species of Thuiaria found in the 1 Foods Hole region. 
A. Stem long and slender, bearing slender branches which subdivide dichotomously. 
Gonangia bimucronate. 
a. Hydrothecse free for about their distal one-third T. argentca. 
a'. Hydrothecse immersed almost to the orifice T. cujircssina. 
A". Stem and branches rigid, the latter stiff and subverticillately arranged. 
Gonangia without mucronate processes on end T. thuja. 
Thuiaria argentea (Ellis & Solander). Fig. 65. 
( Sertularia argentca Ell. & Sol., Zooph., p. 3S.) 
Trophosorne . — Colony breaking up basally into long, slender main 
branches which give off spirally set, closely approximated, secondary 
branches which branch dichotomously, each forming a graceful flabellale 
structure; internodes rather slender, each bearing a group of several 
hydrothecse. Hydrothecse subalternate, tubular, their distal ends curv- 
ing gently outward, so that about the terminal one-third is free; aperture 
armed with two opposite teeth, one much longer than the other. 
Gonosome . — Gonangia with two lateral projections and a central 
terminal orifice. 
Distribution . — Vineyard Sound, Long Island Sound, and other parts 
of the coast. Very common in depths from 1 to 20 fathoms. 
6 
65. Th u iaria argentea ( El 1 . & Sol . ) 
A. Gonangium. 
